Dust
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After just three years of use dust has blocked this laptop heat sink, making the computer unusable |
Dust is a general name for minute
solid particles with
diameter less than
500 micrometers (otherwise see
sand or
granulates) and, more generally, for finely divided
matter. On
Earth, dust occurs in the
atmosphere from various sources:
soil dust lifted up by
wind,
volcanic eruptions, and
pollution are some examples; airborne dust is considered an
aerosol and can have a strong, local
radiative forcing on the atmosphere and significant effects on
climate. In addition, if composed of a flammable substance (such as flour), under some circumstances it can be an explosion hazard.
Dust is responsible for the
lung disease known as
Pneumoconiosis, including
black lung disease that occurs among
coal miners. These have resulted in a number of laws regulating environmental standards for working conditions.
 |
A sample of house dust and hair |
The dust which collects in houses is composed of atmospheric dust combined with dust generated by the inhabitants, mostly from sloughed
skin cells. It can be removed with a
broom, dusting cloth,
vacuum cleaner or by a swipe of one's hand.
A variety of technology has been developed for the purpose of removing accumulated dust in the house. The
air filter is frequently used on inlet of the air ducts to trap dust. These can be supplemented by
air purifiers, including devices that employ
ionization to trap dust particles. Accumulated dust is collected by means of devices such as
dusters and vacuum cleaners.
House dust mites, often found in fibers like carpets and beds, feed on the organic components of house dust. Their feces, in turn, become part of house dust and can provoke allergic reactions in humans.
Dust is also widely present in outer space, where
gas and dust clouds are primary precursors for
planetary systems. The
zodiacal light, seen in the sky at night, is produced by sunlight reflecting off particles of dust in orbit around the
Sun. The tails of
comets are produced by emissions of dust and ionized gas from the body of the comet. Dust also covers planetary bodies, and great
dust storms are produced on
Mars that can cover nearly the entire planet.
Interstellar dust is found between the stars, producing
diffuse nebula and
reflection nebula.
It is thought that dust samples returned from outer space could tell scientists much about the early conditions in the
solar system. Several
spacecraft have been launched in an attempt to gather samples of dust and other materials. Among these was
Stardust which flew past the
comet Wild 2 in
2004 and landed a capsule filled with remains of the comet back in the US in January 2006. The
Japanese
Hayabusa spacecraft is attempting a sample return of dust collected from the surface of an
asteroid.
*In Philip Pullman's bestselling series
His Dark Materials, dust (or '
Dust', as it is spelled in the books) plays an important part by creating a connection between different worlds.
*In the TV
comedy Little Britain, Fat Fighters group leader Marjorie Dawes distinctively instructs the dieters to eat dust as it is 'low in fat'.
*In
JM Barrie's children's novel
Peter Pan, "
pixie dust" is a substance used to help create magical effects.
*In
Clark Ashton Smith's short horror story "The Treader In The Dust" [
1] a scholar unwittingly calls forth a demon which personifies dustiness.
In the
Bible:
*In
Genesis 3:19, Godstates to the couple (representing humanity): :By the sweat of your brow you will eat your food until you return to the ground, since from it you were taken;
for dust you are and to dust you will return. [Emphasis added]This latter clause is used in the
Ash Wednesday service in some churches for the administering of ashes.
*In
Genesis 13:16, God states to
Abram (later Abraham)::I will make your offspring like the dust of the earth, so that if anyone could count the dust, then your offspring could be counted.
*
Dust Bowl*
Particulate*Holmes, Hannah; (2001)
The Secret Life of Dust. Wiley. ISBN 0471377430
